In recent years, vehicles equipped with electric motors (motors) for driving vehicles, such as fuel cell electric cars, hybrid cars and electric cars, have been successively developed. As the electric motors, those including a stator that has a coil disposed thereon, and a rotor that is rotatably supported around an axis on the inner peripheral side of the stator, and has permanent magnets disposed therein are general. As a structure in which the permanent magnets are disposed in the rotor, there is known an IPM (Interior Permanent Magnet) structure in which the permanent magnets are embedded in the rotor by inserting the permanent magnets into insertion holes provided in the rotor core.
For example, Patent Document 1 discloses a permanent magnet type rotor in which conductors and permanent magnets are arranged at a rotor iron core (corresponding to the rotor core of the present application), and the rotor in which the magnetic force of the permanent magnets are increased compared with the related art by placing the permanent magnets adjacent to each other at regular intervals in the circumferential direction and arranging the permanent magnets obliquely with respect to the radial direction of the rotor iron core.
Additionally, Patent Document 2 discloses an embedded magnet type motor in which permanent magnets are embedded in a rotor core, and the rotor core which has a two-piece structure of an inner rotor and an outer rotor, and in which permanent magnets are sandwiched at facing portions of the inner rotor and the outer rotor in a state where the magnets are inclined with respect to the circumferential direction of the rotor core.